Test of Anderson-Stuart model and the 'universal' conductivity in rubidium and cesium silicate glasses

Abstract

An analysis and brief discussion of experimental ionic conductivity 6 and activation energy EA in the binary rubidium and cesium silicate systems is presented, exemplified on 23 and 30 glasses respectively, in a wide composition range (5-45 Rb2O and Cs2O mole%). The Anderson and Stuart model has been considered to describe the variation of activation energy EA with alkali concentration in both alkali-silica systems. In this analysis were considered experimental parameters, like shear modulus G and relative dielectric permittivity e. An "universal" finding is obtained using log sigma x E-A/k(B)T in 51 of 53 glasses considering both alkali systems, where EA is the activation energy for conduction, k(B) is the Boltzmann constant and T is the absolute temperature. This strong correlation by more than 13 (Rb-based glasses) and 15 (Cs-based glasses) orders of magnitude means that a is governed mainly by EA. An explanation for this behavior links ionic conductivity and microscopic structure.